Project Summary/Abstract: Congenital heart disease (CHD) is the most common type of birth defect, accounting for nearly 1% of live births in the US. Even after corrective or palliative surgeries and/or interventions, frequent monitoring, including imaging, is necessary during childhood and beyond. Cardiovascular MRI is an excellent diagnostic tool for children with CHD. MRI offers a clear advantage over computed tomography because it does not involve ionizing radiation. MRI provides clearer visualization of cardiovascular anatomy than echocardiography. Despite these advantages over other imaging modalities, MRI accounts for only 2% of pediatric cardiac diagnostic tests. This underutilization is due to long scan times (typically 60-90 min) and requisite administration of a gadolinium-based contrast agent (GBCA) and general anesthesia (GA), both of which add health risk and healthcare cost. In direct response, we will develop and evaluate rapid cardiovascular MRI and magnetic resonance angiography (MRA) methods that do not require GA or GBCA administration. The scientific premise of this proposal is based on cutting-edge undersampling strategies such as compressed sensing (CS), radial k-space sampling, and simultaneous multi-slice (SMS) excitation which are well-suited for accelerating cardiovascular MRI and MRA pulse sequences. We will synergistically combine these undersampling strategies to develop 2D dynamic MRI methods that ?freeze? physiologic and patient motion and 3D MRA methods with self-navigation of respiratory motion. The specific objectives of this application are: (1) to develop rapid image acquisition and reconstruction methods that will be integrated into a single protocol for imaging pediatric patients without GA or GBCA administration and (2) to test whether a 15-min protocol (objective 1) produces high diagnostic performance in patients with CHD. This study leverages extensive clinical and research resources existing at Ann & Robert H. Lurie Children?s Hospital of Chicago (~1,000 cardiovascular MRI scans per year) and Northwestern University (cardiovascular imaging research). A rapid, free-breathing MRI protocol is a major step forward in MRI technology, because it has the potential to eliminate GA and GBCA administration, while dramatically increasing scan efficiency. Elimination of GA and GBCA administration will reduce associated risks, as well as healthcare costs, and thereby generate greater interest in referring pediatric patients for ?safer? cardiovascular MRI. A faster scan will reduce operational cost and provide a financial incentive for imaging centers to adopt cardiovascular MRI into clinical practice. This R21 application is designed to yield preliminary data needed to pursue a future R01 application aimed at comparing the effectiveness between our new (fast, no GA, no GBCA) and standard-of- care (slow, GA, GBCA) cardiovascular MRI protocols in a diverse pediatric population.